Please explain this to me step by step

Write a function called square(1st) that takes one parameter which is a list of integers and returns a list that contains the square of each element in the given list (see the sample inputs for some examples). We have written the code to read the input from the user in the background. Also, the code challenge will call your function with many input lists and check that it behaves correctly on all of them. Your task is to only define the function as specified which will return the new list which contains the squares of each element. Sample Input 1: 1 2 3 4 Sample Output 1: [1, 4, 9, 16] Sample Input 2: 10 12 15 Sample Output 2: [100, 144, 225]